Consolidated Balance Sheet (Parenthetical) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Common stock, par value (in dollars per share)	$ 5	$ 5
Common stock, authorized (shares)	800,000,000	800,000,000
Common stock, issued (shares)	543,000,000	543,000,000
Common stock held in treasury at cost (shares)	128,000,000	123,000,000
Preferred stock (less than)	$ 0.5	$ 0.5
Portion at Fair Value, Fair Value Disclosure
Loans held for sale, fair value	1,300.0	1,900.0
Loans, fair value	1,400.0	1,500.0
Other assets, fair value	$ 100.0	$ 100.0